Horizontal articulated robot

ABSTRACT

A robot includes an angular velocity sensor installed to a second horizontal arm and for obtaining the angular velocity of the first horizontal arm with respect to a base, and suppresses the vibration of the first horizontal arm by driving a first electric motor based on the angular velocity of the first horizontal arm. In the robot, an electric wire to be connected to a second electric motor incorporated in the second horizontal arm and electric wire to be connected to the angular velocity sensor are laid around through a wiring duct having end portions coupled respectively to the base and the second horizontal arm, disposed outside the first horizontal arm and outside the second horizontal arm, and having a passage leading to the inside of the base and the inside of the second horizontal arm.

BACKGROUND

1. Technical Field

The present invention relates to a horizontal articulated robot equippedwith an angular velocity sensor.

2. Related Art

In the past, there has been known a horizontal articulated robot whichsuppresses vibration caused in the arm using an angular velocity sensorfor detecting the angular velocity of the arm as described inJP-A-2005-242794(Document 1). In the horizontal articulated robotdescribed in Document 1, a first arm rotatable with respect to the baserotates due to the drive force of a first drive source, and at the sametime, the rotational angle of the first drive source is detected by thefirst angle sensor. Further, the angular velocity of the first arm withrespect to the base is detected by an angular velocity sensor mounted onthe first arm. Further, the drive amount of the first drive source iscontrolled based on the angular velocity detected by the angularvelocity sensor so that the vibration caused in the first arm can besuppressed.

Incidentally, the vibration caused in the first arm is generallyamplified by another arm coupled to the first arm, and then reaches anend effector of the horizontal articulated robot. Therefore, in order tosuppress such a vibration of the end effector, it is effective toperform such damping control as described above on the first drivesource.

On the other hand, in order to drive the angular velocity sensordescribed above, it becomes necessary to connect a variety of electricwires such as a wire for supplying the angular velocity sensor withelectricity or a wire for transmitting the detection signal of theangular velocity sensor between the angular velocity sensor and thecontroller. Further, such electric wires are also required for the drivesources besides the angular velocity sensor, and are generally connectedto an external controller through a hollow base. Further, if theconfiguration in which the angular velocity sensor described above ismounted on the first arm is adopted, it results that such an electricwire required to such an angular velocity sensor is also connectedbetween the first arm and the controller through the base.

In this occasion, the track drawn by the first arm with respect to thebase generally includes a larger number of tracks with small curvaturecompared to the tracks drawn by other arms with respect to the base.Therefore, the chances of folding the electric wires drawn from thefirst arm increase, and further, the curvature in the folded portionsalso becomes smaller compared to the electric wires drawn from otherarms. Therefore, it is required for the horizontal articulated robotperforming damping control using the angular velocity sensor to enhancethe durability of such an electric wire connected to the angularvelocity sensor.

SUMMARY

An advantage of some aspects of the invention is to provide a horizontalarticulated robot performing the damping control using an angularvelocity sensor, and capable of enhancing the durability of the electricwire connected to the angular velocity sensor.

An aspect of the invention is directed to a horizontal articulated robotincluding a first arm coupled to a base, a second arm coupled to thebase via at least the first arm, a first drive source incorporated inthe base and adapted to rotate the first arm in a horizontal direction,a second drive source incorporated in the second arm and adapted torotate the second arm in a horizontal direction, and an angular velocitysensor installed to the second arm, wherein the first drive source isdriven based on the angular velocity obtained by the angular velocitysensor to thereby suppress vibration of the first arm.

According to the horizontal articulated robot of this aspect of theinvention, it becomes possible to draw the electric wire to be connectedto the angular velocity sensor from the second arm by installing theangular velocity sensor inside the second arm. The track drawn by thesecond arm with respect to the base generally has a larger curvaturecompared to the track drawn by the first arm with respect to the base.Therefore, since it becomes possible to decrease the chance of foldingthe electric wire to be connected to the angular velocity sensor, and toprevent the curvature of the folded portions of the electric wire to beconnected to the angular velocity sensor from becoming smaller, itbecomes possible to enhance the durability of the electric wire.

The horizontal articulated robot of the above aspect of the inventionmay be configured to further include a piping member having one endcoupled to the base and the other end coupled to the second arm,disposed outside the first arm and outside the second arm, and having apassage leading to an inside of the base and an inside of the secondarm, and an electric wire to be connected to the second drive source andan electric wire to be connected to the angular velocity sensor are laidaround through the piping member.

According to the horizontal articulated robot of the configurationdescribed above, the electric wire to be connected to the second drivesource and the electric wire to be connected to the angular velocitysensor are laid around from the inside of the second arm to the insideof the base through the passage provided to the piping member. Accordingto such a configuration, in order to fold the electric wire to beconnected to the angular velocity sensor, it is required to fold theelectric wire to be connected to the second drive source and the pipingmember at the same time. Therefore, since it becomes possible todecrease the chance of folding the electric wire to be connected to theangular velocity sensor, and to prevent the curvature of the foldedportions of the electric wire to be connected to the angular velocitysensor from becoming smaller, it becomes possible to further enhance thedurability of the electric wire.

The horizontal articulated robot of the above aspect of the inventionmay be configured to further include a belt disposed inside the secondarm, and adapted to transmit a drive force of a third drive source to adisplacement member displaced with respect to the second arm, and theangular velocity sensor is disposed above the belt.

Here, if the angular velocity sensor is installed below the belt drivenby the third drive source, there is a possibility that a foreign mattergenerated from the belt drops and then adheres to the angular velocitysensor. In contrast, according to the configuration described above,even if the foreign matter is generated from the belt, the foreignmatter can be prevented from adhering to the angular velocity sensor.

The horizontal articulated robot of the above aspect of the inventionmay be configured such that a connection section between the pipingmember and the second arm is disposed on an upper side of the secondarm.

Here, if the connection section between the second arm and the pipingmember is disposed in the region of the second arm on the horizontaldirection side, the connection section and the peripheral region of theend portion of the piping member, the end portion being located near tothe second arm, overlap the rotational path of the second arm, andtherefore, might pose an impediment for the second arm to rotate. Incontrast, according to the configuration described above, the connectionsection between the second arm and the piping member, and the peripheralregion of the end portion of the piping member, the end portion beinglocated near to the second arm, are disposed at positions neveroverlapping the rotational path of the second arm. As a result, thesmooth rotation of the second arm can be realized.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described with reference to the accompanyingdrawings, wherein like numbers reference like elements.

FIG. 1 is a front view showing a front structure of a robot according toan embodiment of the invention.

FIG. 2 is a perspective view showing an internal structure of a secondhorizontal arm, and is a perspective view showing a state with an armcover detached.

DESCRIPTION OF AN EXEMPLARY EMBODIMENT

Hereinafter, a horizontal articulated robot according to an embodimentof the invention will be explained with reference to FIGS. 1 and 2.

As shown in FIG. 1, in the robot 10 as the horizontal articulated robot,a base end portion of a first horizontal arm 12 as a first arm rotatingaround a shaft center C1 along the vertical direction with respect to abase 11 is coupled to an upper end portion of the base 11 to be mountedon, for example, a floor. Inside the base 11, there are disposed a firstelectric motor 13 as a first drive source for rotating the firsthorizontal arm 12, and a reduction gear 14 coupled to a rotating shaft13a of the first electric motor and having an output shaft 14afixedly-coupled to the first horizontal arm 12. Further, the firsthorizontal arm 12 rotates in a horizontal direction, namely makes ahorizontal turn, with respect to the base 11 due to the drive force ofthe first electric motor 13 transmitted thereto via the reduction gear14. The first horizontal arm 12 is made of a metal material such as castiron, and has high rigidity in, for example, the longitudinal directionand the circling direction.

To the tip portion of the first horizontal arm 12, there is coupled abase end section of an arm main body 15 a provided to a secondhorizontal arm 15 as a second arm rotating around the shaft center C2along the vertical direction with respect to the first horizontal arm12. Inside the second horizontal arm 15, there are installed a secondelectric motor 16 as a second drive source for rotating the secondhorizontal arm 15, and a reduction gear 17 coupled to the rotating shaft16 a of the second electric motor 16 and having an output shaft 17 afixedly coupled to the first horizontal arm 12. Further, the secondhorizontal arm 15 rotates in a horizontal direction, namely makes ahorizontal turn, around the shaft center C2 with respect to the firsthorizontal arm 12 due to the drive force of the second electric motor 16transmitted thereto via the reduction gear 17. The second horizontal arm15 is made of a metal material such as cast iron, and has high rigidityin, for example, the longitudinal direction and the circling direction.

The second horizontal arm 15 has an arm cover 18 for covering the upperside of the arm main body 15 a from the base end portion to the tipportion thereof including the second electric motor 16 and so on. Thearm cover 18 is made of, for example, a resin material, and protects thedevices such as the second electric motor 16 while preventing the dustgenerated by the devices from flying to the periphery. The secondhorizontal arm 15 according to the present embodiment is composed of thearm main body 15 a and the arm cover 18.

On the tip portion of the second horizontal arm 15, there is disposed anup/down rotating shaft 19 as a displacement member penetrating the armmain body 15 a and the arm cover 18 and displaced with respect to thesecond horizontal arm 15. The up/down rotating shaft 19 is a columnarshaft member, and is provided with a ball screw groove and a splinegroove not shown formed on the circumferential surface thereof. As shownin FIG. 2, the up/down rotating shaft 19 is inserted so that the splinegroove thereof is fitted into the center of a spline nut 19S disposed atthe tip portion of the second horizontal arm 15, and that the ball screwgroove thereof is screwed into the center of a ball screw nut 19Bdisposed also at the tip portion of the second horizontal arm 15. Thus,the up/down rotating shaft 19 is supported rotatably with respect to thesecond horizontal arm 15, and movably in a vertical direction.

As shown in FIG. 2, inside the second horizontal arm 15, there isinstalled a rotary motor 20 as a third drive source. The rotary motor 20has the drive force transmitted to the spline nut 19S via a belt 21. Inother words, the up/down rotating shaft 19 is positively and negativelyrotated around the own shaft center C3 along a vertical direction inaccordance with the spline nut 19S being rotated positively andnegatively by the rotary motor 20 described above.

Inside the second horizontal arm 15, there is installed a lifting motor23 also as the third drive source. The lifting motor 23 has the driveforce transmitted to the ball screw nut 19B via a belt 24. In otherwords, the up/down rotating shaft 19 performs lifting and loweringmovements in vertical directions in accordance with the ball screw nut19B being rotated positively and negatively by the lifting motor 23described above. Then, a work section 25 as the lower end portionthereof is lifted and lowered in the vertical directions due to thelifting and lowering movements thereof.

The work section 25 of the up/down rotating shaft 19 is arranged to beable to be attached with a tool such as a device for gripping a conveyedobject or a device for processing a processed object. Further, the robotis arranged to convey parts or process parts using the respective toolsattached to the work section 25.

Further, as shown in FIG. 2, inside the second horizontal arm 15, thereis installed an angular velocity sensor 30 for measuring the angularvelocity of the second horizontal arm 15. As the angular velocity sensor30, there is used a vibratory gyroscope using a quartz crystal vibratorin the present embodiment. The angular velocity sensor 30 is supportedby a plurality of supporting legs 31 erected inside the secondhorizontal arm 15 so that the posture thereof can be adjusted.

Here, if a foreign matter is generated from the belts 21, 24 due todrive of at least one of the rotary motor 20 and the lifting motor 23described above, the foreign matter drops below the belts 21, 24.Therefore, if the angular velocity sensor 30 is installed below thebelts 21, 24, it becomes easy for the foreign matter to adhere to theangular velocity sensor 30. In contrast, in the present embodiment, theangular velocity sensor 30 supported by the supporting legs 31 is alwaysdisposed above the belts 21, 24 regardless of the rotational angles ofthe first horizontal arm 12 and the second horizontal arm 15. Therefore,even if at least one of the rotary motor 20 and the lifting motor 23 isdriven, the foreign matter dropping from the belts 21, 24 can beprevented from adhering to the angular velocity sensor 30.

Further, as shown in FIG. 2, to the upper portion of the secondhorizontal arm 15, there is coupled one end of a wiring duct 33 havingflexibility as a piping member having the other end coupled to the base11. The wiring duct 33 has a tubular shape, and the one end thereof isrotatably coupled to the second horizontal arm 15, while the other endis rotatably coupled to the base 11. The wiring duct 33 is provided witha passage 34 leading to the inside of the second horizontal arm 15 andthe inside of the base 11. Further, an electric wire 35 connected to thesecond electric motor 16 installed inside the second horizontal arm 15and an electric wire 36 connected to the angular velocity sensor 30 arelaid around from the inside of the second horizontal arm 15 to theinside of the base 11 through the passage 34 described above.

It should be noted that although not shown in FIGS. 1 and 2, electricwire connected to the rotary motor 20 and electric wire connected to thelifting motor 23 are also laid around to the inside of the base 11through the passage 34 described above. Further, inside the passage 34,it is preferable that the materials of the constituents of the electricwires and the layout of the electric wires are considered so that theelectric wire 36 is not electrically affected by other electric wires.

Incidentally, it is also possible for the connection section between thewiring duct 33 and the second horizontal arm 15 to be disposed at aposition shifted to the horizontal direction side of the secondhorizontal arm 15, namely on the front side or the back side of thedrawing sheet in FIG. 1. However, in such a configuration, theconnection section and the peripheral region of the end portion of thewiring duct 33, the end portion being located near to the secondhorizontal arm 15, overlap the rotational path of the second horizontalarm 15, and therefore, might pose an impediment for the secondhorizontal arm 15 to rotate. In contrast, in the present embodiment, theconnection section between the second horizontal arm 15 and the wiringduct 33 are disposed on the upper portion of the second horizontal arm15. Therefore, the connection section is disposed so that the peripheralregion of the end portion of the wiring duct 33, the end portion beinglocated near to the second horizontal arm 15, does not overlap therotational path of the second horizontal arm 15. Thus, the smoothrotation of the second horizontal arm 15 can be realized.

Further, the angular velocity sensor 30 is a sensor for detecting theangular velocity of the second horizontal arm 15, and is therefore onlyrequired to be installed in the second horizontal arm 15. However, ifthe angular sensor is installed outside the second horizontal arm 15instead of the inside of the second horizontal arm 15, a separateconfiguration for laying the electric wire connected to the angularvelocity sensor 30 around to the inside of the second horizontal arm 15becomes necessary in order to lay the electric wires around through thepassage 34 of the wiring duct 33. Since the configuration for laying theelectric wire 36 around to the inside of the second horizontal arm 15becomes unnecessary by installing the angular velocity sensor 30 insidethe second horizontal arm 15 as in the case of the present embodiment,simplification of the configuration of the second horizontal arm 15, andconsequently of the configuration of the robot 10, can be achieved.

Further, the electric wires laid around to the inside of the base 11 arebundled in the inside of the base 11 to thereby be laid around to acontroller 40, which is installed in the outside of the base 11 toperform overall control of the robot 10, together with an electric wire37 connected to the first electric motor 13 described above.

The controller 40 controls the drive amount of the first electric motor13 based on the signal input from the angular velocity sensor 30 so thatthe vibration of the second horizontal arm 15 is suppressed. Forexample, the controller 40 obtains the rotational angle of the firstelectric motor 13 from the encoder installed in the first electric motor13, and further obtains the rotational angle of the second electricmotor 16 from the encoder installed in the second electric motor 16.Further, the controller 40 estimates the angular velocity of the firsthorizontal arm 12 based on the angular velocity of the second horizontalarm 15, the rotational angle of the first electric motor 13, therotational angle of the second electric motor 16, and so on to therebycontrol the drive amount of the first electric motor 13 so that thevibration of the first horizontal arm 12 is suppressed.

As explained hereinabove, according to the robot 10 related to thepresent embodiment, the advantages recited as follows can be obtained.

1. According to the robot 10 of the embodiment described above, sincethe angular velocity sensor 30 for controlling the drive amount of thefirst electric motor 13 is disposed in the second horizontal arm 15, theelectric wire 36 to be connected to the angular velocity sensor 30 isdrawn from the second horizontal arm 15. Here, the track drawn by thesecond horizontal arm 15 to the base 11 has larger curvature withrespect to the base 11 compared to the track drawn by the firsthorizontal arm 12 to the base 11. Therefore, since it becomes possibleto decrease the chance of folding the electric wire 36 to be connectedto the angular velocity sensor 30, and to prevent the curvature of thefolded portions of the electric wire 36 to be connected to the angularvelocity sensor 30 from becoming smaller, it becomes possible to enhancethe durability of the electric wire 36.

2. According to the robot 10 of the embodiment described above, theelectric wire 35 to be connected to the second electric motor 16 and theelectric wire 36 to be connected to the angular velocity sensor 30 arelaid around from the inside of the second horizontal arm 15 to theinside of the base 11 through the passage 34 provided to the wiring duct33. The electric wire 36 to be connected to the angular velocity sensor30 can be laid around from the second horizontal arm 15 to the base 11using the wiring duct 33 coupled to both of the second horizontal arm 15and the base 11 as realized in such a configuration. Since it isrequired to fold the wiring duct 33 in addition to the electric wire 36in order to fold the electric wire 36, it is possible to reduce thechances of folding the electric wire 36, and to prevent the curvature ofthe folded portions from becoming smaller. As a result, it becomespossible to further enhance the durability of the electric wire.

Further, since the electric wires 35, 36 to be connected respectively tothe second electric motor 16 and the angular velocity sensor 30 are laidaround the inside of the base 11, there are laid around inside the base11 not only the electric wire 37 to be connected to the first electricmotor but also the electric wires 35, 36 to be connected respectively tothe second electric motor 16 and the angular velocity sensor 30.Therefore, it is also possible to lay these electric wires 35 through 37around to the outside of the base 11 in a lump.

3. In the embodiment described above, the angular velocity sensor 30 isdisposed inside the second horizontal arm 15. Thus, there is no need toprovide the configuration for laying the electric wire 36 to beconnected to the angular velocity sensor 30 around to the secondhorizontal arm 15, which is required in the case of installing theangular velocity sensor 30 on the lower surface of the arm main body 15a. As a result, simplification of the configuration of the secondhorizontal arm 15, and consequently the configuration of the robot 10,can be achieved.

4. According to the robot 10 of the embodiment described above, sincethe angular velocity sensor 30 is disposed above the belts 21, 24, theforeign matter dropping from the belts 21, 24 can be prevented fromadhering to the angular velocity sensor 30.

5. According to the robot 10 of the embodiment described above, sincethe connection section between the second horizontal arm 15 and thewiring duct 33 is disposed on the upper side of the second horizontalarm 15, the peripheral region of the end portion of the wiring duct 33,the end portion being near to the second horizontal arm 15, is disposedat a position never overlapping the rotational path of the secondhorizontal arm 15. As a result, the smooth rotation of the secondhorizontal arm 15 can be realized.

It should be noted that the embodiment described above can be put intopractice with the following modifications if necessary.

-   -   In the embodiment described above, the connection section        between the second horizontal arm 15 and the wiring duct 33 is        disposed on the upper side of the second horizontal arm 15,        namely at the position not overlapping the rotational path of        the second horizontal arm 15. It is also possible to modify this        configuration to thereby dispose the connection section so as to        overlap the rotational path of the second horizontal arm 15 from        the viewpoint of laying the electric wires 35, 36 to be        connected to the second electric motor 16 and the angular        velocity sensor 30 around to the inside of the base 11 through        the passage 34. Even with such a configuration, advantages        equivalent to the advantages recited as 1 through 4 above can be        obtained.    -   In the embodiment described above, the angular velocity sensor        30 is disposed above the belts 21, 24 for transmitting the drive        forces of the rotary motor 20 and the lifting motor 23. It is        also possible to modify this configuration to thereby dispose        the angular velocity sensor 30 below the belts 21, 24. Even with        such a configuration, advantages equivalent to the advantages        recited as 1 through 3 above can be obtained.    -   In the robot 10 of the embodiment described above, there is        disposed the wiring duct 33 provided with the passage 34 through        which the electric wire 36 is laid around. Besides this        configuration, it is also possible for the robot 10 to have a        configuration in which the wiring duct 33 is reluctantly omitted        to thereby expose the electric wire extending from the angular        velocity sensor 30 to the base 11. Even with such a        configuration, an advantage equivalent to the advantage recited        as 1 above can be obtained providing that a variety of electric        wires extending from the arm is generally drawn to the outside        through the base, and the angular velocity sensor for        suppressing the vibration of the first arm is installed to the        second arm.    -   It is also possible for the robot 10 of the embodiment described        above to have a configuration further including another arm        intervening between the first horizontal arm 12 and the second        horizontal arm 15.    -   The angular velocity sensor 30 of the embodiment described above        is disposed inside the second horizontal arm 15. However, since        the angular velocity sensor is only required to be installed to        the second horizontal arm 15, the installation position is not        limited to the inside of the second horizontal arm 15. Even with        such a configuration, the advantages recited as 1 and 2 above        can be obtained.    -   The robot 10 according to the embodiment described above has the        wiring duct 33 having a tubular shape provided with the passage        34 as a piping member. Besides this configuration, any piping        member capable of housing the electric wire and preventing the        electric wire from getting entangled during the operation of the        robot 10 can be adopted, and the shape thereof is not limited to        the tubular shape. Further, the piping member is only required        to have flexibility, and the material thereof is not        particularly limited.    -   As the angular velocity sensor 30 of the embodiment described        above, a vibratory gyroscope using a quartz crystal vibrator is        adopted. Besides this configuration, the angular velocity sensor        is only required to be able to measure the angular velocity of        the second horizontal arm 15 with respect to the base 11, and a        rotary gyroscope, a gas gyroscope, a ring-laser gyroscope, and        so on can also be adopted.    -   The suppression of the vibration of the first horizontal arm 12        is only required to be achieved by controlling the drive amount        of the first electric motor 13 using the detection result of the        angular velocity sensor 30, and it is also possible to adopt the        process of, for example, detecting the vibration of the second        horizontal arm 15 from the detection result of the angular        velocity sensor 30 and the rotational angle of the second        electric motor 16 to thereby suppress the vibration under the        estimation that the vibration thus detected is the vibration of        the first horizontal arm 12. Further, in the case in which the        first horizontal arm 12 and the second horizontal arm 15 are        fixed on the same axis line, and the first horizontal arm 12        rotates alone, it is also possible to adopt the process of, for        example, estimating the vibration of the first horizontal arm 12        based on the detection result of the angular velocity sensor 30        and the rotational angle of the first electric motor 13, and        then suppressing the vibration.

The entire disclosure of Japanese Patent Application No. 2011-035859,filed Feb. 22, 2011 is expressly incorporated by reference herein.

What is claimed is:
 1. A horizontal articulated robot comprising: a first arm coupled to a base; a second arm coupled to the base via at least the first arm; a first drive source incorporated in the base and adapted to rotate the first arm in a horizontal direction; a second drive source incorporated in the second arm and adapted to rotate the second arm in a horizontal direction; an angular velocity sensor installed to the second arm; and a belt disposed inside the second arm, and adapted to transmit a drive force of a third drive source to a displacement member displaced with respect to the second arm, wherein the first drive source is driven based on the angular velocity obtained by the angular velocity sensor to thereby suppress vibration of the first arm, and the angular velocity sensor is disposed above the belt.
 2. The horizontal articulated robot according to claim 1, further comprising: a piping member having one end coupled to the base and the other end coupled to the second arm, disposed outside the first arm and outside the second arm, and having a passage leading to an inside of the base and an inside of the second arm, wherein an electric wire to be connected to the second drive source and an electric wire to be connected to the angular velocity sensor are laid around through the piping member.
 3. The horizontal articulated robot according to claim 2, wherein a connection section between the piping member and the second arm is disposed on an upper side of the second arm. 